Willi Forst plays a former Guards officer who embarasses the singer Tilla Morland (Liane Haid) by walking off during one of her musical performances, but he later explains the reasons for this behaviour and is hired as her private secretary. But although a mutual love develops between the two, there are circumstances which make a happy outcome impossible. So while the film has many very funny moments, it is misleading to call it a comedy; a great romance with the melodrama played down would perhaps fit better.

I don't hesitate to call "Das Lied ist aus" one of the great masterpieces of early German cinema. It is one of the best and most stylish of all the Weimar musical sound films, and it's unusual for its strongly melancholic undertone and unhappy ending. It can also be regarded as one of the defining films for the team of actor Willi Forst, director Geza von Bolváry and scriptwriter Walter Reisch. Forst fully established his screen persona here: the witty, elegant, but also fragile and thoughtful gentleman, although he was a much too versatile actor to be pinned-down to such keywords. Forst is paired here with the equally stunning Liane Haid, very charming and womanly, and the chemistry these two have has rarely been achieved again in later films with Forst (but check out "Der Prinz von Arkadien" with the same team!). 

And of course there's the music by Robert Stolz, who wrote some of his very best songs for this film: the melancholic "Frag' nicht warum", the witty "Wenn das Wörtchen wenn nicht wär", the even today still famous "Adieu mein kleiner Gardeoffizier" and also "Die Liebe ist wie ein Tonfilm", an early instance of reflecting on the newly developed medium of the sound film and on the dreams created by the cinema in general.